Clinical Characteristics of Patients With Anti‐Signal Recognition Particle Antibody: A Cohort Study

BACKGROUND: Anti-signal recognition particle (anti-SRP) antibodies are myositis-specific autoantibodies associated with immune-mediated necrotizing myopathy. This study was undertaken to better understand how patients with anti-SRP antibodies have been managed at our tertiary centre and to assess the spectrum of clinical features and outcomes in routine clinical practice. METHODS: We conducted a retrospective evaluation of 25 patients with anti-SRP antibodies identified via line-blot immunoassay at a tertiary care centre (2019-2024). Demographic, clinical, serological, and imaging data were reviewed. RESULTS: The group of patients had a mean age of 60.1 years, with a female-to-male ratio of 10:15. Eight patients (32%) were diagnosed with myositis, primarily presenting with proximal muscle weakness. Interstitial lung disease was observed in 53% of the group of patients, and 50% of the subset of patients with myositis. Coexisting myositis-specific autoantibodies were present in 32%, and 48% had positive antinuclear antibody titres (≥ 1:400). Cardiac involvement was reported in two myositis patients. Corticosteroids, often combined with mycophenolate mofetil or other immunosuppressants, formed the basis of treatment. CONCLUSION: Anti-SRP antibodies are associated with a heterogeneous clinical spectrum, with many patients lacking myositis features. There was a high prevalence of coexisting autoantibodies. Further studies are needed to elucidate the pathogenic role of anti-SRP and optimise management strategies.